An arch with a flat lower or inner curve.
- ‘Sansovino could have designed a rusticated flat arch for the herms to carry, or even a simple Tuscan entablature without metopes and triglyphs, but instead he chose the Doric.’
- ‘The result is a stone frame - 28 stone columns with flat arches between them - supporting the roof and the reinforced concrete floor slabs.’
- ‘A concrete and glass form rises from the second floor of the concourse and bulges out from its base, forming a flat arch.’
- ‘The style of architecture is very clearly Tudor as is characterised by the flat arches and the shape of the roofs of the two towers.’